Screen Rant are running a feature that claim, based on an interview with a stuntman who worked on the set of Thor: The Dark World, that they may have deduced the identity of the film's central antagonists.

In an interview geared toward discussing the craft of stunt work and how much of it requires actual acting chops, James Grogan reportedly told I Review Too that during his time on the set of the Marvel sequel, the film's director instructed him that he would need to be an elf in a shot:

“The other day...I was working on Thor 2. I had a load of stunt guys in and the director came in and he said ‘Look, we want you all to be elves,’ and I was like ‘What the hell is an elf anyway?’ and he said ‘I want you all to walk around like these supernatural animals,’ honestly it was the most ridiculous thing ever but you just have to not be self aware and get on with it.”

Based on Grogan's description of his character as an "elf," Screen Rant are guessing that the villains of the piece might actually be Malekith the Accursed and the Dark Elves, who inhabit the realm of Svartalfheim and spend quite a lot of their time in the comics attempting to take over Asgard.

Says Screen Rant:

"In the comics, Malekith has made several bids to conquer Asgard; he’s partnered with Loki, attempted to unleash the Cask of Ancient Winters (Frost Giant weapon seen in Thor 1), has impersonated key members of Asgard in attempts to take the throne, and has even possessed the minds of Earthlings."

It's likely the alliance with Loki that's most likely to rear its head in the film, if anything; while many have speculated that Loki might be headed for a redemption arc in this movie, that's not guaranteed--and even if it's the case, that doesn't preclude him trying to pull something either early or late in the film. The mind-control element of the characters is frankly not a very attractive proposition after The Avengers, in which we saw so much of that out of Loki himself.